1. Field of the Invention
The present invention relates to a process and apparatus for the treatment of waste water and, more particularly, relates to a process and apparatus which will effectuate the combined biological and physical-chemical treatment of waste effluents to remove biological oxygen demand (BOD) and provide a clarified discharge through the application of an oxidation process. More specifically, the invention relates to a combined biological and physical-chemical process and apparatus for treating the aqueous waste materials or effluent discharged from beverage bottling plants or installations.
2. Discussion of the Prior Art
At present, aqueous waste material or effluent from various bottling plants and installations is discharged to receiving waters or drains without any treatment being applied thereto. Alternatively, waste or effluents are treated through the selective utilization of two basic biological systems, such as the "activated sludge" and the "trickling element" (also known as a trickling filter) processes, both of which are proven systems having been currently employed for a lengthy period of time. However, the known activated sludge process is readily upset by intermittent flows or slug loadings, and equalization of applied flows or loadings in waste treatment processes of this type has proven to be difficult and expensive. Moreover, when applied to bottling installations, particularly soft drink and brewery plants, the activated sludge process has resulted in bulking problems due to the presence of carbohydrate concentrations in the effluent, and in the destruction of the biological waste treating process caused by the discharge of caustic materials into the system. In essence, since bottling plants generally process and recondition for repeated use "returnable" bottles, a primary source of aqueous waste material or effluents lies in the bottle washing system, whereas secondary sources of effluents are caused by the wash-down of the filler-crowner units, periodic wash-down of plant tanks and piping at the end of each day's production or on product changeover, plant floor area drainage, and solids emanating from the plant water treatment facilities.
Essentially, the plant waste treatment systems are protected by suitable process strainers against damage by major particulate solids, such as glass particles caused by bottle breakage, and other large-sized impurities. Usually, bottling plants do not discharge oils, greases or other deleterious substances so that, in this instance, they are not of any particular significance. In practice it has been found that returnable bottles which are conveyed to a bottle washing machine are sprayed by liquid jets for initial cleaning thereof and to remove debris, and are then soaked in a caustic soda solution, following which they are sprayed with potable water to remove any caustic residuals. The wastes or effluents from the initial washing operation, which is generally referred to as "pre-rinse", are collected separately and usually represent 15% of the continuous waste flow and contain more than 70% of the BOD (biological oxygen damand) loading of a bottling plant.
Effluents from the subsequent bottle washing process, commonly referred to as "final rinse", are collected after the bottles are conveyed through a warm and cold water wash to remove the last particles of caustic soda, with the final rinse water generally representing a major portion of the continuous waste flow and containing not more than 20% of the BOD loading.
Another fraction of the effluent or waste, commonly referred to as "bottling and support area drainage", is discharged during washing of the filler-crowner units, and during plant tank and piping cleaning and sanitizing. Wash-down of the bottling process equipment is effected at the end of each day's production or at the time of product changeover. The estimated waste from these sources is not part of a continuous waste flow but is periodic, and usually may represent approximately 5% of the total daily waste or effluent volume, and about 4% of the total daily BOD loading.
Effluents from the water treatment facilities, referred to as "backwash water", result from backwashing of the sand carbon filtration units and from regeneration of water softeners. Based on plant piping arrangements, the unit washing and backwashing of filters sequences are not carried out concurrently but, rather, backwashing is performed at the end of each day's operation.
Thereafter, the effluents or aqueous waste materials from each of the four primary effluent sources, namely, pre-rinse, final rinse, bottling and support area drainage, and backwash water, is separately piped to the waste treatment facilities for separate handling and processing.
Investigations have indicated that excellent results are obtained in the treatment of aqueous waste materials or effluents, particularly when applied to beverage or soft drink bottling plants, by a combination of biological and physical-chemical process steps wherein a trickling element is utilized in combination with the subsequent aeration and chemical treatment of the effluent. In that instance, particularly advantageous results are obtained through the intermediary of a trickling element employed in a roughing process for the removal of biochemical oxygen demand (BOD), followed by a sequence of oxidation processes employing aeration and ozonation to thereby produce an acceptable effluent meeting the most demanding and stringent environmental standards and conditions.